[Influence of lipopolysaccharide on the expression of Toll-like receptor 4 in human bronchial epithelium cell in patients with chronic obstructive pulmonary disease]

Abstract

Objective: To investigate the influence of lipopolysaccharide (LPS) on the inflammation mediated by Toll-like receptor 4 (TLR4), and the role of LPS in the pathogenesis of chronic obstructive pulmonary disease (COPD) in the primary cultured human bronchial cells in patients with COPD.

Methods: Human bronchial cells were isolated and cultured from 24 patients who undergone pneumonectomy. The patients were allocated into COPD group, non-COPD smoking group and non-COPD, non-smoking group based on their lung functions and smoking history; and 8 patients each. 100 microg/L LPS was applied to stimulate the primarily cultured cells. Flow cytometry was adopted to detect the TLR4 on surfaces of bronchial epithelial cells, and reverse transcriptase-polymerase chain reaction (RT-PCR) was used to measure the level of TLR4 mRNA in the primarily cultured human bronchial epithelial cells.

Results: Fewer fluorescence positive cells of TLR4 were observed in non-COPD smoking group [(1.52 +/- 0.06)%] and non-COPD, non-smoking group [(1.78 +/- 0.06)%], and more positive cells of TLR4 were found in the COPD group [(10.23 +/- 0.58)%, q = 5.61, 5.38, all P < 0.05]. Fluorescence positive cells of TLR4 and fluorescence intensity were significantly increased in the non-COPD smoking group and non-COPD, non-smoking group after LPS stimulation [(10.69 +/- 0.74)%, (11.28 +/- 0.68)%, q = 9.58, 8.98, all P < 0.05], but significant increasing of fluorescence positive cells were not found in the COPD group after LPS stimulation [(11.89 +/- 0.89)%, q = 1.95, P > 0.05]. TLR4 mRNA (absorbance value) level were very low in both non-COPD smoking group (0.147 +/- 0.008) and non-COPD, non-smoking group (0.152 +/- 0.013), whereas it was higher in COPD group (0.359 +/- 0.032, q = 5.12, 4.99, all P < 0.05). TLR4 mRNA was found significantly increased in both non-COPD smoking group and non-COPD, non-smoking group after LPS stimulation (0.425 +/- 0.037, 0.418 +/- 0.035, q = 4.58, 4.65, all P < 0.05); but significant increasing of TLR4 mRNA was not found in the COPD group after LPS stimulation (0.398 +/- 0.028, q = 0.86, P > 0.05).

Conclusion: Chronic inflammation and LPS stimulation induce fluorescence positive cells of TLR4 and the level of TLR4 mRNA increases in the primarily cultured human bronchial epithelial cells obtained from patients with COPD, which may play an important role in the pathogenesis of COPD.